PROJECT SUMMARY The purpose of this K01 Mentored Research Scientist Development application is to develop Dr. Kathryn Lancaster's career as an independent investigator in conducting long-term, meaningful research at the intersection of substance use and blood-borne infections among women. This K01 will provide Dr. Lancaster with the necessary support to extend her skills to truly transformative and important new directions in 1) multilevel data collection and analyses, 2) biological and clinical aspects of hepatitis C virus (HCV) acquisition and disease progression, 3) stated-preference theory and application of discrete choice experiments, and 4) building capacity for community-academic partnerships for addressing injection drug use in a new sociocultural environment? rural Appalachia. In support of these skills, Dr. Lancaster is supported by an outstanding interdisciplinary team of mentors with robust research portfolios, successful mentorship histories, and a strong track record of collaboration. This team includes: Dr. Christopher Browning (Primary Mentor), Dr. Carlos Malvestutto (Co-Mentor), Dr. John F P Bridges (Co-Mentor), and Dr. April Young (Co-Mentor). Injection drug use and HCV among young women is dramatically rising in rural settings within the United States. HCV risks and utilization of harm reduction services, like syringe service programs (SSP), within each injection partnership vary due to complex cultural and gender norms. The social milieu that impact young women who inject drugs (YWID) requires an in-depth understanding of how partnership-level factors and preferences for SSP shape HCV risk reduction in rural settings. The goal of this study understand the role of injection partnership-level factors on HCV risk and measure preferences for SSP among YWID in rural Appalachian Ohio (Scioto, Pike, and Jackson Counties). Dr. Lancaster will leverage the NIDA-funded National Rural Opioid Initiative (UG3) study infrastructure and community-academic partnerships to specifically: 1) Describe the contribution of injection partnership-level factors on HCV risk behaviors among YWID in rural Appalachia; 2) Determine the effect of injection partnership-level factors on HCV risk behaviors among YWID in rural Appalachia; and 3) Elicit preferences for SSP among YWID in rural Appalachia. In-depth interviews with YWID will be conducted to explore the how HCV risk behaviors may vary within and across injection partnerships. Intensive granular, temporal data data will be collected quarterly using in-person behavioral surveys and augmented with monthly ecological momentary assessments to capture injection partnership-level factors and HCV risk behaviors in real-time. A formal elicitation of stated preferences for SSP will illuminate attributes for services tailored for YWID. The training and research plan will produce preliminary data to inform a NIDA R01 application to conduct a multisite, randomized controlled trial evaluating the effectiveness of a tailored harm reduction package, addressing injection partnership factors that will reduce HCV risk among YWID rural Appalachian.